This invention relates to apparatus for shifting the phase of an AC signal. More particularly, it is concerned with phase shifting apparatus in which the amount of the phase shift is variable in predetermined amounts.
The phase of an AC signal may be shifted in various ways. The signal may be conducted through lengths of transmission line or delay lines or may be processed by digital phase shifting circuitry. These elements may be employed in arrangements which permit varying the amount of phase shift obtained. However, known techniques utilizing elements of the foregoing type involve problems of physical size, difficulties in preserving the amplitude information of the AC signal, and problems in precisely controlling the phase shift over a wide range.